1. Field of the Invention
This invention relates to chemical analysis tests, and, in particular, a device for detecting the presence or quantity of analytes while also measuring the pH of sample solutions containing the analytes.
2. Background
The presence or quantity of specific molecules or substances (xe2x80x9canalytesxe2x80x9d) in a solution can be determined through several known means, such as immunoassays or non-immunoassays. Depending on the nature of the assay, an active reagent is chosen from a group of reagents that are reactive with the analyte. Such reactive reagents include substances that react with the analyte, enzymes or enzymatic substrates of the analyte, or binding reagents of the analyte, such as antibodies or antigens.
Knowledge of the presence or quantity of analytes contained in bodily fluids is especially useful. Among other things, results of analyte testing can be used to diagnose medical conditions and to measure the concentration of drugs or toxic substances in a human or animal subject. Analyte test results can also be used to monitor appropriate levels of therapeutic agents or for other purposes.
In some situations, the presence or quantity of the analyte depends upon the pH of the solution. pH can be measured in a variety of different ways, including via color changes in organic compounds. Such compounds include methyl red, methyl orange, bromphenol blue, etc. When the presence of certain drugs, such as cocaine or methamphetamine, are assayed from saliva, the pH can assist the person administering the test in correlating the cocaine or methamphetamine in the saliva to the blood levels of the drug. See Malamud, D., Saliva as a Diagnostic Fluid, Br. Med. J. 305: 207-208 (1990); Mandel, I. D., The Diagnostic Uses of Saliva, J. Oral Pathol. Med., 19: 119-125 (1990); Mandel, I. D., xe2x80x9cSalivary Diagnosis: Promises, Promises,xe2x80x9d in Malamud, D. and Tabak, L. (Eds.) Saliva as a Diagnostic Fluid, Vol. 694: Annals of the New York Academy of Sciences, New York: The New York Academy of Sciences (1993), pp. 1-8; Kopecky, E. et al., Correlation of Morphine Sulfate in Blood Plasma and Saliva in Pediatric Patients, Ther. Drug Monitoring, 19 no. 5: 530-534 (1997); Leonard, J., et al., Correlation of Buccal Mucosal Transudate Collected with a Buccal Swab and Urine Levels of Cocaine, J. Addictive Beh., 13 no. 1: 27-31 (1994); Mendelson, J., et al., Bioavailability of Sublingual Buprenorphine, J. Clin. Pharm., 37:31-37 (1997). Such correlation of saliva concentrations to blood levels is important in situations such as detoxification, medical monitoring situations or in law enforcement situations.
Presently, blood levels of specific drugs are usually determined through invasive methods, such as venipuncture or finger-stick. The disadvantages of such invasive methods include the need for trained medical personnel, sterilization, discomfort, length of time required, prevention of contact with the blood by the phlebotomist and any other handlers, frequent multiple attempts at obtaining an appropriate sample. Consequently, a device that can use other bodily fluids and correlate them to blood levels represents a significant advancement over previous devices.
This invention involves a device for the concurrent measurement of pH and an analyte in solution where the presence or quantity of the analyte is related to the pH of the solution. Such solutions could include, but are not limited to, saliva, urine, whole blood, serum plasma, mucous or mixtures of other substances in liquid. The device is a single unit that contains a pH measurement section, an assay section, and a color coded pH comparison section that allows the pH to be interpreted. The simplicity of the device and the ability to quickly and accurately make appropriate measurements with pH correlation is a significant improvement over previous devices.